Heat treating furnace with circulated gas quench



Jan. 31, 1967 H- N. lPSEN 3,301,541

HEAT TREATING FURNACE WITH CIRCULATED GAS QUENCH Filed June 12, 1964 3 Sheets-Sheet l g Arrow HarolcL Y1. lpJe'rL 0 J 4.44 day 4 as.

H. N. IPSEN Jan. 31, 1967 HEAT TREATING FURNACE WITH CIRCULATED GAS QUENCH 5 Sheets-Sheet 2 Filed June 12, 1964 .llullllll I ll .lllIlL pbl: irpl MVEMFOD qlamsd Q1. r n. 4 Mq W J44 M United States Patent 7" 3,301,541 HEAT TREATING FURNACE WITH CIRCULATED GAS QUENCH Harold N. Ipsen, Rockford, Ill.; The Illinois National Bank & Trust Co., Rockford, Ill., executor of Harold N. Ipsen, deceased Filed June 12, 1964, Ser. No. 374,790 12 Claims. (Cl. 266-) This invention relates to furnaces for heating metal workpieces in a work chamber and subsequently cooling the workpieces by circulating a cooling gas through the chamber and around the workpieces therein. More particularly, the invention relates to furnaces of the type in which'the work chamber is defined by a box-like enclosure having insulated reflecting walls and disposed Within a vacuum-tight vessel provided with means outside the enclosure for cooling the gas circulating through the enclosure, the enclosure being formed with inlet and outlet ports on opposite sides of the work. chamber to carry gas into the chamber and then back through the vessel outside the chamber for recooling.

In such furnaces, means such as a fan outside one of the ports in the enclosure is provided to circulate the gas within the vessel, and insulated reflecting members are mounted in positions overlying the ports to block all direct radiation paths from the work chamberthrough the inlet and outlet ports. Thus, the reflecting members and the enclosure walls minimize heat loss to the cooling chamber outside the enclosure.

The general object of the present invention is to provide a new and improved furnace of the above character in which the heating is more uniform and the quenching is faster and more effective than in prior furnaces of this general type.

Another object is to substantially reduce the adverse effect of the outlet ports and the reflecting members on the uniformity of secondary heating of the workpieces by heat reflected by and radiated from the enclosure walls.

Still another object is to obtain a full and unobstructed flow of gas through one or both ports during quenching for a more powerful blast of gas through the work and more rapid cooling of the work.

A further object is to increase the effectiveness of the gas-circulating fan by increasing the density of the circulating gas in advance of the fan.

Other objects and advantages of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings, in which FIGURE 1 is a fragmentary longitudinal cross-sectional view of a furnace embodying the novel features of the present invention, the view being taken substantially along the line 11 of FIG. 2.

- walls.

FIG. 2 is a fragmentary cross-sectional view taken 1 along the line 22 of FIG. 1.

FIG. 3 is a cross-sectional view generally similar to FIG. 1 showing another embodiment of the invention.

As shown in the drawings for purposes of illustration, the invention is embodied in a furnace for heating metal workpieces in a chamber 10 formed by a box-like en closure 11 disposed within a horizontal, vacuum-tight outer vessel 12, and subsequently cooling or quenching the workpieces in the work chamber to obtain certain desirable physical properties of the metal. To protect the finish of the workpieces, they are heated in a protective atmosphere, usually a vacuum treated by a suitable pumping apparatus (not shown) that communicates with the interior of the vessel through a port 13 (FIG. 2). The work is quenched in a flow of non-oxidizing gas admitted 3,301,541 Patented Jan. 31, 1967 into the vessel at the end of the heating portion of the cycle, the gas being admitted into the vessel through a port 14 (FIG. 1) communicating through a suitable control valve with a source such as a pressurized tank (not shown).

During treatment, workpieces are disposed in a tray or basket 15 supported in the work chamber 10 on a hearth formed by two angle-shaped rails 17 extending longitudinally of the furnace above the bottom wall of the enclosure and supported on horizontal elements 18 spanning the sidewalls of the enclosure. Heat is provided by a heater herein comprising a plurality of con ventional radiant heating elements 19 surrounding the hearth to produce uniform heating of the work load on the hearth. As shown in FIG. 2, the heating elements are adapted to be connected to a suitable control unit through insulators 20 spanning the space between the enclosure and the vessel and connected to power feedthrough elements 21 sealed in the vessel wall.

In this instance, the vessel 12 is formed by radially spaced inner and outer concentric shells 22 and 23 secured at their ends to rings 24 which close the openings into the space between the shells to form a Water jacket in which coolant is circulated during operation of the furnace. The rear end of the vessel is closed by a dished rear cover 25 and the front end is closed by a similar front cover 27 having a central opening 28 normally closed by an access door 29 which may be hinged at one side on the front cover for swinging outwardly into an' open position.

As shown in FIG. 2, the inner enclosure 11 is supported in the vessel 12 in spaced relation with the inner shell 22 of the vessel on two horizontal rails 30 extending longitudinally of the vessel along the sidewalls of the enclosure and mounted on the inner ends of two sets of brackets 31 projecting inwardly from the inner shell. Rollers 32 journaled on pins 33 carried on the enclosure sidewalls roll on the rails and thus mount the enclosure for easy installation and removal through the front end of the vessel when the front cover 27 is removed.

To confine heat within the work chamber 10 while the workpieces are being heated and thereby obtain optimum utilization of the heat and also prevent heating of the vessel 12 and the outer chamber 34 therein, the enclosure walls comprise sheet metal shells having inner surfaces forming diffusion or heat shields 35, 37 and 38 which reflect heat radiated by the heating elements back toward the center of the work chamber. The shells are filled with heat resistant insulating material 39 such as alumina wool which retards heat conduction through the Thus, a substantial portion of the radiant heat produced by the heating elements is reflected back into the chamber by the shields and most of that which is absorbed is held close to the inner surfaces of the enclosure. As a result, the enclosure walls are heated and themselves become secondary sources of heat for heat ing the work load from all sides.

In the front wall of the enclosure 11 is an opening 40 through which workpieces are loaded onto the hearth rails 17. An inner door 41 carried on the outer door 29 overlies and closes this opening when the outer door is in place. To permit visual inspection of the Work load during treatment, a sight opening 42 is formed in the inner door in alinement with a scope 43 projecting through the front cover. Normally the sight opening is covered by a block 44 which is swingable out of the way by means of a lever 45 journaled in the front cover and connected to the block by the linkage shown in FIG. 1. Both the block and the inner door are similar in construction to the remainder of the enclosure walls to reflect heat and reduce heat loss by conduction;

through an inlet port 47 and an outlet port 48 formed in the enclosure on opposite sides of the hearth. Herein, in the ports are rectangular openings in the top and bottom walls of the enclosure directly above and below the hearth. The means for circulating the gas takes the form of a fan 49 mounted on the vessel 12 above the outlet port with the fan blades 50 radiating from the lower end of the shaft 51 of a motor 52 (FIG. 2) and rotatable in a plane spaced from the top wall of the enclosure. The fan motor is disposed outside the vessel and supported on a base 53 fitted in an opening in the top of the vessel with the motor shaft projecting through the base into the vessel. A cup-shaped case 54 covers the fan motor and is sealed against the base to prevent air leakage into the vessel around the motor shaft.

When the fan is in operation, the blades 50 force gas outwardly away from the outlet port 48 in all directions. Deflector plates 55 and 57 extending from the outside of the enclosure to the inner shell 22 at the front and rear ends of the enclosure direct all this gas downwardly along the inside cylindrical wall of the vessel and around the enclosure toward the inlet port 47. Thus, the fan induces a 'flow of gas upwardly through the inlet port and the work chamber.

As the gas flows through the passages formed by the chamber 34 outside the enclosure, it is cooled by contact with the inner shell 22 and also by cooling coils 58 (FIG. 2) disposed in the path followed by the gas. Herein, the cooling coils are disposed between the inner shell and the enclosure on both sides of the fan, and a suitable coolant is circulated through the coils through fittings 59 projecting through the rear cover 25.

Loss of heat through the two ports 47 and 48 during heating of the work load is prevented by two members 60 and 61 which overlie the ports to block radiation through the ports and reflectheat back into the work chamber 10. These members also comprise sheet metal shells having inner reflecting walls 62 and 63 filled with insulation 64. In the past, such reflecting members have been mounted as baflles spaced outwardly from the adjacent walls of the enclosure far enough to define indirect paths for the flow of gas around the bafiles and through the ports during the quenching portion of the furnace cycle.

The present invention contemplates a new and improved furnace of this general type in which the work load may be heated more uniformly and quenched more rapidly than in the prior furnaces. For this purpose, at least one of the members 60, 61, and preferably both of them, are disposed in positions closely overlying and substantially closing the inlet and outlet ports 47 and 48 during heating to minimize the cffectof the ports on the uniformity of heating within the work chamber, and are movable out of these overlying positions during quenching to permit a full and unobstructed flow of gas through the ports and the work chamber for apowerful and direct blast of quench-ing gas through the work. Thus, in contrast to the so-called baflles of prior furnaces, the members 60 and '61 constitute movable bungs for selectively and completely opening or closing the ports. When the ports are closed, the secondary heating action of the bungs is similar'to the heating action of the adjacent portions of the enclosure walls, and when they are open, the bungs provide no resistance to gas flow into and through the work chamber.

In this instance, the bottom bung 60 is sized and shaped to fit upwardly within the inlet port 47 and bring its inner reflecting surface '62 into a plane close to the lower inside wall of the work chamber. For this purpose, the four sidewalls of the bung are formed with inner portions 64' and 65 inclined to converge inwardly as shown in FIGS. 1 and 2. to fit closely within the correspondingly inclined outer portions 67 .and 68 of the four enclosure walls defining the inlet port. The outer portions 69 of the bung sidewalls project horizontally beyond the outer margins 4 of the inlet port far enough to overlie any space that is left between the bung and the walls of the port when the bung is in the closed position.

From this closed position, the bottom bung 60 is movable downwardly to an out-of-the-way position spaced well below the bottom wall of the enclosure as shown in broken lines in FIG. 2. To control the position of the bung, an operator in the form of a pneumatic cylinder 70 is disposed below the vessel with its piston rod 71 extending upwardly through a fitting 72 into the vessel and connected at 73 to the underside of the bung. Thus, as the piston rod moves endwise up and down, it correspondingly raises and lowers the bung. The latter is guided during such movement along upright rods 74 depending from the underside of the enclosure and forming a skeleton framework below the enclosure. Preferably, a pad 75 is mounted on the lower ends of the guide rods to support the bung in its lowered position in which the bung is spaced far enough belowthe enclosure to have little, if any, effect on the air flowing around the enclosure and into the inlet port.

The top bung 61 is disposed closely adjacent the top wall of the enclosure in its closed position, between the enclosure and the fan 49, and is large enough to c0mpletely cover the port 48 and overhang the top wall of the enclosure on all sides of the port. From this closed position, the bung is movable horizontally to the rear to the open position shown in broken lines in FIG. 1 in which the outlet port is completely uncovered. To support the bung for movement between these two positions, rollers 77 (FIG. 2) journaled on the hung on pins 78 fast in the sidewalls of the bung ride on two horizontal tracks formed by the tops of two angle bars 79 extending rearwardly along each side of the path the bung follows during back and forth movement.

In this instance, the angle bars 79 are supported on the upright sidewalls of a sheet metal hood 80 having an open bottom overlying the outlet port 48 and a top opening 81 disposed above the outlet port and centered beneath the fan 49. The hood extends rearwardly from the outlet port and has an open rear end toward which the bung moves during opening and through which the bung projects in its open position. To move the bung 61 back and forth along the tracks, a second pneumatic operator is disposed outside the rear cover 25 of the vessel -12 with its piston rod '82 extending forwardly through a fitting 83 in the cover and into the hood -80 with its forward end connected to the rear wall of the bung. Thus, back and forth movement of the piston 84 in the cylinder 85 shifts the top bung back and forth under the hood to open and close the outlet port. When the bung is open, the hood forms an outlet passage between the outlet port and the underside of the fan.

While manually operable controls may be provided for the various furnace mechanism including the vacuum pump, the heating elements 19, the bung operators, and the gas-supply valve, the furnace preferably is programmed for fully automatic operation in a well known manner. Whether it is manual or automatic, the typical furnace cycle is started with the fan 49 turned off, a work load on the hearth, the inner and outer doors 29 and 41 in place, and both bungs 60 and 61 in the closed positions shown in full in the drawings. Then the vessel is evacuated through the port 13 and the heating elements are energized to begin the heating portion of the cycle under the selected treating conditions for the particular treatment being performed.

With the bungs 60 and 61 in the closed positions, the work load on the hearth is heated rapidly and uniformly by direct radiation from the heating elements 19 and also by the heat reflected and radiated from all portions of the enclosure walls. Because the bungs are closely adjacent the enclosure walls, the differences in the amount of heat radiated and reflected by the bungs, as compared to the rest of the enclosure walls, are negligible and cold spots in the work load are eliminated.

When heating is completed, the vessel 12 is loaded with gas through the port 14, the two bungs 60 and 61 are shifted to their open positions, and the fan 49 is energized and coolant is circulated in the coils 58 to begin the cooling portion of the cycle. The fan draws gas upwardly through the outlet port 48 and the hood 80 through the opening 81, and forces the gas outwardly and downwardly past the cooling coils, through the cooling chamber 34 to the inlet port 47, and through the work chamber 10. The open ports permit a full and unobstructed flow of gas through the inlet port, the work chamber, and the outlet port with minimum turbulence and flow resistance for optimum gas circulation by a fan 49 and a motor 52 of a given size. In other words, the fan operates at optimum efficiency with the bungs open, and produces a powerful blast of cooling gas directly through the work load to cool the latter rapidly to below the critical temperature.

An alternate form of the invention is illustrated in FIG. 3 in which the cylindrical outer vessel 87 is disposed in a vertical position and the heating chamber 88 is formed within a coaxial cylindrical enclosure 89 having sidewalls comprising a cylindrical sheet 90 forming an inner heatrefiecting lining, a layer 91 of insulation such as alumina Wool outside the lining, and an outer cylindrical retaining wall spaced from the inner shell 92 of the vessel to define a flow passage and cooling chamber 93 between the enclosure and the vessel. The insulated bottom wall 94 of the enclosure is formed with a central inlet opening 95 and is supported on upright posts 97 which support the enclosure above the downwardly dished lower cover 98 of the vessel. A hollow base structure 99 supports the vessel in the upright position.

The upper end of the vessel 87 is closed by a downwardly opening cup-shaped upper cover 100 with a ring 101 encircling its rim in position to fit against and seal against a similar ring 102 encircling the upper end of the vessel shells 92 and 103. An insulated top wall 105 defining an outlet port 106 is disposed over the open upper end of the enclosure 89 and supported on the cover 100 on a series of brackets 107 fast on the inside of the cover rim and on the top wall so as to support the latter for removal from the enclosure as the cover is removed from the vessel.

Near the bottom of the heating chamber 88 is a hearth 108 formed by horizontal rails adapted to support the charge to be heated. A plurality of heating elements 109 .are angularly spaced around the walls of the enclosure to surround the work on the hearth and are connected through insulators 110 to power feed-through elements 111 extending through and sealed in the vessel 87.

As before, the inlet and outlet ports 95 and 106 are covered by movable bungs 112 and 113 having inner reflecting surfaces 114 backed by insulation 115 and adapted to be moved into out-of-the-way positions indicated in broken lines in FIG. 3 for a free flow of gas through the ports during quenching. In this instance, both the inlet and outlet openings and the associated bungs are circular in cross-section and the inner portions of the bungs are of reduced size to fit into the associated ports and bring the reflecting surfaces 114 close to the planes of the inner enclosure walls. The lower bung 112 is sized to fit upwardly into the inlet port and is moved up and down by an operator including a cylinder 117 supported in the hollow base 99 and a piston rod 118 connected to the underside of the bottom bung.

The fan 119 is located at the top of the cover 110 above the outlet port 106 and the :motor is mounted within a sealed case 120outside the cover. A hood 121 is disposed between the fan and the top wall 105 of the enclosure with the open bottom of the hood fast on the top wall around the outlet port and with an outlet opening 122 in the top of the hood immediately below the fan. In this instance, the top bung 113 is moved up and down within the hood between the two positions shown in FIG. 3 by a suitable operator (not shown) connected to the bung by means of rods 123 extending downwardly through the cover. The cross-sectional area of the hood is substantially greater than the area of the bung to leave a substantial clearance in the hood around the open bung.

Thus, when the bungs 112 and 113 are open and the fan is in operation, gas is drawn out of the work chamber 88 around the top bung and through the hood 121 and is forced by the fan 119 outwardly within the cover 100, past cooling coils 124 within the cover, then downwardly through the outer chamber 93, and finally upwardly through the inlet opening for circulation past the work on the hearth 108. The open bungs permit a free flow of gas through the work chamber for rapid and effective cooling of the work.

To further increase the effectiveness of the fan in circulating gas through the furnace, additional cooling elements 125 are provided in the air passage formed between the open upper bung 113 and the portion of the hood 121 adjacent the hood opening 122. It will be seen that these cooling elements are protected from exposure to radiation from the chamber 88 whether the bung 113 is open or closed, and heated gases drawn out of the work chamber during quenching must fiow past these elements before reaching the fan. Accordingly, the quenching gas is cooled and its density is increased in advance of the fan with the result that the effectiveness of the fan in circulating the gas is increased.

I claim as my invention:

1. In a heat treating furnace for first heating and then cooling workpieces, the combination of, a hollow vacuumtight vessel, an enclosure within said vessel having walls comprising an inner diffusion shield backed by a layer of thermal insulation and forming an insulated work chamber within the enclosure and a cooling chamber in said vessel outside the enclosure, means defining an inlet port and an outlet port in the enclosure walls on opposite sides of said work chamber and communicating with said cooling chamber, at least one selectively operable heater in said work chamber for heating workpieces therein, two bungs disposed in positions overlying and substantially closing said ports and having diffusion shields facing toward said heater and backed by a layer of thermal insulation thereby to confine heat within said enclosure while workpieces are being heated therein, means supporting said bungs in said overlying positions and for movement away from said ports into out-of-the-way positions for full and unobstructed gas flow through the ports, means for cooling gas in said cooling chamber, and selectively operable means for circulating gas within said vessel successively through said cooling chamber, said inlet port, said work chamber, said outlet port and then back through said cooling chamber when said bungs are in said out-of-the-way positions.

2. In a furnace for first heating and then cooling a work load, the combination of, a hollow vacuum-tight vessel, a box-like walled enclosure within said vessel defining a work chamber within said enclosure and a cooling chamber within the vessel outside the enclosure, a selectively operable radiant heater in said work chamber for heating a work load therein, inlet and outlet ports in the enclosure Walls spaced apart across said work chamber and communicating with said cooling chamber; first and second bungs substantially closing said inlet port and said outlet port, respectively, to confine heat within said work chamber during heating, means mounting each of said bungs for movement away from the respective port into an out-of-the-way position spaced from the port to permit a full and unobstructed flow of gas therethrough, selectively operable means for circulating gas within said vessel and successively through said cooling chamber, said inlet port, said Work chamber, said outlet port, and then back through said cooling chamber, and means for cooling gas in said cooling chamber.

3. A furnace as defined in claim 2 in which said circulating means includes a fan spaced outwardly from said outlet port and the closed position of said first bung and operable when activated to draw gas through said outlet port and force the gas through said cooling chamber to said inlet port. 3

4. A furnace as defined in claim 3 in which said first bung in its closed position is disposed closely adjacent the outside of said enclosure between said fan and said outlet port, and is movable laterally along the adjacent enclosure wall into its out-of-the-way position spaced from said fan and said outlet port.

5. A furnace as defined in claim 4 further including a hood disposed between said fan and said outlet port and having a first opening overlying said outlet port and a second opening adjacent said fan, said first bung being disposed in said hood between the fan and the outlet port in its closed position and being spaced laterally from the fan and the port in its out-of-the-way position whereby the fan draws gas from said outlet port through said hood.

6. A furnace as defined in claim 2 in which said second bung in its closed position is fitted within said inlet port with its inner surface adjacent the inner surface of the adjacent wall of the enclosure, and is movable outwardly away from said enclosure and said inlet port to its outof-the-way position.

7. In a furnace for first heating a work load in a vacuum and then gas quenching the work load, the combination of, a hollow vessel, a walled enclosure within said vessel defining a work chamber within said enclosure, a selectively operable radiant heater insaid chamber for heating a work load therein, inlet and outlet ports in the walls of said enclosure spaced apart across said chamber and communicating with the interior of said vessel outside said enclosure to permit a flow of gas through the chamber, a hood outside said enclosure surrounding said outlet port and having an outlet opening spaced from the outlet port and communicating therewith through said hood, a member disposed within said hood overlying and substantially closing said outlet port to block heat radiation therethrough during heating of the work load, means supporting said member for movement from its closed position away from said outlet port into an out-of-the-way position spaced from the out-let port to permit a free flow of gas between said chamber and said vessel through said outlet port, a fan within said vessel and outside said hood adjacent said outlet opening for drawing gas from said chamber through said hood and circulating the gas through the vessel to said inlet port, and cooling means in said hood for cooling the gas and increasing its density before it reaches said fan.

8. A furnace as defined in claim 7 in which said member overlies said outlet port in both of said positions and is substantially smaller in cross-sectional area than said hood thereby to cooperate with the hood in its out-of-theway position in defining an air passage between said outlet port and said out-let opening, said cooling elements being disposed in said hood between said outlet opening and the out-of-the-way position of said member.

9. In a heat treating furnace, the combination of, a hollow vessel, a walled enclosure within said vessel defining a work chamber, selectively operable means for heating workpieces within said chamber, inlet and outlet ports in the walls of said enclosure spaced apart across said chamber, a hood outside said enclosure surrounding said outlet port and having an outlet opening spaced from the outlet port and communicating therewith through said hood, a member disposed within said hood in overlying relation with said outlet port and cooperating with the hood to define a passage for the flow of gas through the hood from said chamber, a fan outside said hood -adjacent said outlet opening for drawing gas through the hood, and cooling means in said passage for cooling the gas and increasing its density before it reaches said fan.

10. In a furnace for first heating and then cooling a work load, the combination of, a hollow vessel, a walled enclosure within said vessel defining a work chamber within said enclosure and a cooling chamber Within the vessel outside the enclosure, a selectively operable heater in said work chamber for heating a work load therein, inlet and outlet ports in the enclosure walls spaced apart across said work chamber and communicating with said cooling chamber, first and second members overlying said ports to confine heat within said enclosure while the work load is being heated, means to move at least one of said members from a position substantially closing the adjacent port to an out-of-the-way position spaced from the associated port for a full and unobstructed flow of gas through the port during cooling of the work load, selectively operable means for circulating gas within said vessel and successively through said cooling chamber, said inlet port, said work chamber, said outlet port, and then back through said cooling chamber, and means for cooling the gas in said cooling chamber.

11. In a furnace for first heating and then cooling a work load, the combination of, a hollow vessel, a walled enclosure within said vessel defining a work chamber within said enclosure and a cooling chamber within the vessel outside the enclosure, a selectively operable radiant heater in said work chamber for heating a work load therein, inlet and outlet ports in the enclosure walls spaced apart across said work chamber and communicating with said cooling chamber, first and second members having reflecting surfaces overlying said ports closely adjacent said enclosure walls and substantially closing the ports to block heat radiation through the ports and confine heat within said work chamber during heating of the work load therein, and means supporting said members for movement out of the overlying positions into out-ofthe-way positions spaced from said ports for a full and unobstructed flow of gas through the ports during cooling of the work load.

12. In a furnace for first heating a work load in a vacuum and then gas quenching the work load, the combination of, a hollow vessel, a walled enclosure within said vessel defining a Work chamber within said enclosure, a selectively operable radiant heater in said chamber for heating a work load therein, first and second ports in the walls of said enclosure spaced apart across said chamber and communicating with the interior of said vessel outside the enclosure to permit a flow of gas through the chamber, a member overlying and substantially closing said first port to block heat radiation through the latter during heating of the work load, means supporting said member for movement out of its overlying position into an out-ofthe-way position spaced from said first port to permit a full and unobstructed flow of gas between said vessel interior and said chamber through said first port, and selectively operable means for circulating quenching gas within said vessel through said ports and said work chamber to quench the work load after heating.

References Cited by the Examiner UNITED STATES PATENTS 3,002,735 10/1961 Baker et a1 263 40 3,168,607 2/1965 Greene 266-5 3,219,331 11/1965 Ipsen 266-5 FOREIGN PATENTS 1,171,877 6/1964 Germany.

JOHN F. CAMPBELL, Primary Examiner.

J. D. HOBART, Assistant Examiner.

Disclaimer 3,301,541.Ham0ld N. I psen, Rockford, Ill. HEAT TREATING FURNACE WITH CIRCULATED GAS QUENCH. Patent dated J an. 31, 1967. Disclaimer filed Nov. 5, 1971, by the assignee, Alco Standard Carporation. Hereby enters this disclaimer to all the claims of said patent.

[Oflicz'al Gazette March 7, 1.972.] 

11. IN A FURNACE FOR FIRST HEATING AND THEN COOLING A WORK LOAD, THE COMBINATION OF, A HOLLOW VESSEL, A WALLED ENCLOSURE WITHIN SAID VESSEL DEFINING A WORK CHAMBER WITHIN SAID ENCLOSURE AND A COOLING CHAMBER WITHIN THE VESSEL OUTSIDE THE ENCLOSURE, A SELECTIVELY OPERABLE RADIANT HEATER IN SAID WORK CHAMBER FOR HEATING A WORK LOAD THEREIN, INLET AND OUTLET PORTS IN THE ENCLOSURE WALLS SPACED APART ACROSS SAID WORK CHAMBER AND COMMUNICATING WITH SAID COOLING CHAMBER, FIRST AND SECOND MEMBERS HAVING REFLECTING SURFACES OVERLYING SAID PORTS CLOSELY ADJACENT SAID ENCLOSURE WALLS AND SUBSTANTIALLY CLOSING THE PORTS TO BLOCK HEAT RADIATION THROUGH THE PORTS AND CONFINE HEAT WITHIN SAID WORK CHAMBER DURING HEATING OF THE WORK LOAD THEREIN, AND MEANS SUPPORTING SAID MEMBERS FOR MOVEMENT OUT OF THE OVERLYING POSITIONS INTO OUT-OFTHE-WAY POSITIONS SPACED FROM SAID PORTS FOR A FULL AND UNOBSTRUCTED FLOW OF GAS THROUGH THE PORTS DURING COOLING OF THE WORK LOAD. 